In computer storage arrays (also referred to herein as storage systems or storage subsystems), disk partitioning and data volume management are used to manage physical storage devices such as hard disk drives. In disk partitioning, a single storage device is divided into multiple logical storage regions referred to as partitions, thereby treating one physical storage device as if it were multiple disks. Data volume management provides a method of allocating space on mass-storage devices that is more flexible than conventional partitioning schemes. In particular, a volume manager can concatenate, stripe together or otherwise combine regions (a region is a sequence of bytes having a specific length, typically one megabyte) into larger virtual regions that administrators can re-size or move, potentially without interrupting system use.
Storage facilities can use snapshots for disaster recovery planning. A snapshot may be a copy of data residing on a data volume that is created at a particular point in time. Since a full backup of a large data set can take a long time to complete, a snapshot may define the dataset to be backed up. Data associated with the snapshot is static, and is therefore protected from any subsequent changes to the data on the data volume (e.g., a database update).
One typical implementation of a snapshot is called a “pointer snapshot.” A pointer snapshot records an index of data locations to be protected on the data volume. Pointer snapshots can be created fairly quickly and require far less storage space than is required to maintain a separate copy of the snapshot data.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.